Reaching towards a visual target is ubiquitous in daily life. The task seems effortless, yet requires substantial processing to accomplish. Our goal is to better understand the visuospatial information processing underlying action. For this purpose, we use visually-guided reaching in the non-human primate as a model system. Our first aim is to determine the specific contributions of posterior parietal areas to the kinematics and dynamics of visually-guided reaching. We will use a novel method to precisely localize the sites of reversible injections placed throughout the intraparietal sulcus. After each injection we will test animals on a panel of tasks (reaches, saccades and visual search) and then image the site of inactivation. This method is comprehensive and better indicates the true functional contributions of parietal areas than can be achieved through single unit recording. Our second aim is to identify and quantify components of activity in posterior parietal cortex that are related to bimanual coordination. Primates commonly use the two arms together to accomplish tasks that are difficult or impossible to perform with a one arm. Clinical evidence suggests a role of the parietal cortex in bimanual coordination. Our results will help distinguish between two specific models of how bimanual coordination might be manifest at the level of individual neurons. Our third aim is to quantify the activity of posterior parietal neurons during evaluation of targets and decision-making in performing reaches, and to compare that activity to that observed during decision-making for saccadic eye movements. Recent work has suggested a specific model for decision-making for saccadic eye movements. Our results will indicate whether parietal circuits for target evaluation and decision circuits are the same or different for different kinds of action (reaches versus saccades). Achieving these aims will help us understand the early processes involved in sensory to motor transformation, motor coordination, and decision-making. The results will critically inform the devise of rational strategies for aiding recovery from strokes and other central damage, as well as the design of optimal brain interfaces for a new generation of prosthetic devices. PUBLIC HEALTH RELEVANCE The central goal of this proposal is to understand the early processing of visuospatial information for visually- guided reaching. Achieving this goal will help clinicians to understand and ultimately reverse the damage caused by parietal and occipital strokes and other brain trauma. Understanding how the brain generates and represents plans for movement is also critical to the development of promising neuroprosthetics for patients with amputations, spinal cord injuries, and disorders such as amyotrophic lateral sclerosis.